Parasite Burdens and the Flynn Effect

The Flynn Effect is the real, not-test-based increase in IQ seen in first-world countries, about 3 IQ points a decade. In the last couple decades the effect has leveled off in much of developed world. There's a lot of discussion over why this should be.

One obvious candidate is parasite burden. As countries develop, public sanitation gets better, and public health improves. If it's public health (pathogens plus nutrition) and offering standardized schooling to all, you would expect to see an eventual plateau in developed countries, and the developing countries begin to follow their trend.

Any parasite which directly damages the brain is an obvious candidate as one causative agent. This is especially interesting when you read that up to one-third of people in, e.g. Peru, have radiographic evidence of neurocysticerosis - tapeworm damage in the brain. This study shows that of people with evidence of the disease, 18.2% of them in childhood have IQ < 70. Starting to connect dots, we can start making an estimate of IQ improvement from eradication of neurocysticercosis alone.

• Let's assume that (as the Peruvian study showed) 33% of people have neurocysticerosis.
  
  
• Let's assume that of the people with neurocysticercosis, 18.2% (4% of the total population) have IQ < 70, the mean IQ is 69. This is obviously simple and actually quite conservative, but the higher we make the mean number for this subgroup, the more modest the effect of eradicating neuroscysticercosis.
  
  
• Let's also assume that the 70 and above IQ folks are evenly distributed between 70 and 100. Also simplifying, but I doubt neurocysticercosis makes many people smarter.
  
  
• With those assumptions, then a 3-point IQ increase in the general pouplation could be brought about by a one-third decrease in NC cases.
  
  
• Of course the 3-point IQ trend goes on for more than 3 decades (when all three-thirds of would-be neurocysticercosis patients were prevented from getting it) so it can't just be that.

To test the hypothesis, we could look at average IQ increases going forward in developing countries currently getting de-wormed. You could also look at existing Flynn Effect curves for the developed world and compare it against the % population getting on clean public water supplies. Of course it's hardly controversial that lower parasite burden would correlate with better outcomes, and indeed the de-worming projects have already shown an improvement in school attendance in participating areas. And while parasite diseases cause massive human suffering, this is still interesting even just by purely pragmatic reasons: a country's economic well-being is linked to the average IQ.

The Lack of Real-World Money Pumps: How Intransitive Preferences Do and Do Not Distort Behavior

In economics and other areas of applied rationality, the problem with having intransitive preferences - where you prefer x to y, and y to z, but z to x - is that you can supposedly be made into a money pump, by taking advantage of these irrational preferences. Indeed I'd seen claims online of people who were subjects of psychology or economics experiments actually knowing that this was happening to them, but being unable to stop themselves. This seemed both intuitively far-fetched, as well as something which would be constantly exploited, especially if it was a trait that existed differentially in the population.

I had encountered this idea some years ago in the rationalist canon, but I had never been able to think of examples where it really happened. Imagine my joy when I thought I had finally run across it when, after dinner one night, my (irrational) toddler demonstrated intransitive preferences when eating M&M's and trading with me. She prefers green over orange, orange over brown, and brown over green. Here it is!, I thought. A money pump! But exactly how could I benefit from this?

As it turned out, there was no way to money-pump her, and might not be a way to ever meaningfully money-pump anybody. But to illustrate the point I'll give you a hypothetical example of how it could work. This hypothetical example alters her real behavior considerably - to see what I changed and why it could not work in the real world, skip ahead to "Where Are the Real Money Pumps?" in bold below.

Say we both start out with 12 green, 12 orange, and 12 brown, and assume the following preference rules (individual exchange rates):

I have transitive preferences: I like green twice as much as orange, which I like twice as much as brown. (1 green = 2 orange = 4 brown)

She has intransitive preferences: she likes green twice as much as orange, which she likes twice as much as brown, which she likes twice as much as green, etc.) In fact, I would argue that she has a subtype of intransitive preferences, cyclic preferences: with intransitive preferences you can also just say that there is no value on something and it can't be used in trade. (Though irrational by Von Neumann-Morgenstern and other standards, this is in fact how normal human beings behave; in contrast, when someone will put a price on anything, that person is called a psychopath.)

It helps to see the specifics of how you can take advantage of someone with cyclic preferences, but it's dry and boring, so I'll include it in a "supplement" at the end if you're interested and don't just want to take my word for it. Suffice it to say after at most 7 trades, I would have all the M&M's except for two brown ones.


THEN WHERE ARE THESE MONEY PUMPS? I.E., WHERE ARE THE SYSTEMS OF CYCLIC PREFERENCES THAT ARE ECONOMICALLY TAKEN ADVANTAGE OF?

I went looking for cases in the real world where people get money-pumped, and found:
a) none, and
b) I'm not the only one who has noticed this gap.

In fact money-pumping seems to be an entirely theoretical risk, predicted deductively from rationality models. So what's going on? Likely some combination of:

1. People are irrational and their preferences are a mess, but they aren't neatly cyclical like this. In fact we should expect that most intransitive preferences are just that - they have no relation to any other preferences - therefore precluding a cyclic system of intransitive preferences. That is, sets of cyclic preferences are a subset of intransitive preferences, but because of the nature of intransitive preferences (basically they're a mess with little relation to each other or even consistency on short time scales), cyclic preferences are very rare or nonexistent in the real world.
   
   
2. Humans have many heuristics that can cause reasoning errors, but that also must have been on net beneficial to our ancestors, and (sometimes) they only make sense in the context of their environment. For example, we like to punish wrongdoers, to the point where we will spend more resources to do it, even when the damage has already been done. This seems irrational, unless you realize that there are not many limited-round-games in life, and if there was someone doing bad things in your tribe fifty thousand years ago, it made sense to invest those punishment-resources now to deter further wrongdoing later. A more germane example is the endowment effect, which is a heuristic that clearly has the effect of keeping people from getting taken advantage of in markets with asymmetric information. I expect that with cyclic preferences, there is a meta-preference that usually acts like a circuit-breaker for this sort of thing, for example just thinking about the goods in dollar figures. Of course, you could rightly object, if someone can do that, they don't really have cyclic preferences, since the dollar is like a color of M&M that doesn't admit of intransitive valuation - and you're right! Which is why people don't actually get money-pumped! In this same way, I expect that even my toddler would notice her overall number of M&M's is shrinking and mine is growing and at some point say she's not playing this stupid game anymore.
   
   
3. There actually are some cyclic preference-sets revealed by people engaging in repetitive behavior that makes their life consistently worse. This includes compulsive gambling, junk food, substance abuse, and staying in abusive relationships (or seeking out new ones.) It's interesting that these aren't about trading with currency, or at least don't centrally involve explicit trade or currency exchange, which are relatively new things in terms of evolutionary psychology, and something where along with learning them explicitly, we have developed learned defenses against being taken advantage of (as noted above.) Even in those cases where there appear to be cyclic preferences, these are better understood as predictably shifting preferences (due to things like future discounting), but this is a semantic distinction since they have the same outcome.

SO WHERE DO WE SEE IRRATIONAL BEHAVIOR DUE TO INTRANSITIVE PREFERENCES?

Clashes between the system of transitive preference systems - speaking broadly, the economy - and intransitive preferences are somewhat rare, but they occur, even when they are not cyclic. You don't think of people repeating abusive relationships as part of the economy, but that's a great example of intransitive preferences. Gambling and substance use are part of the economy, but at the fringes (it's interesting that societies usually have prohibitions or regulations about trading the same sorts of things, things which involve strongly affective parts of our cognition and behavior like gambling, sex, drugs, and firearms.)

Some psychopaths recognize the intransitive nature of most humans' valuation of other human life (it's "priceless"), and take hostages who they will kill unless they are given money or some other objective. In those cases, many humans magically overcome our intransitiveness and kill the hostage-takers, or allow the hostage-takers to kill their victims in order to avoid negotiating in the future.

A fortunately more common but unfortunately probably more intractable problem is healthcare: about 70% of healthcare dollars in the U.S. spent by someone are spent in the last 6 months of that person's life. We could spend more and more getting additional minutes at the end of life. Unless we're going to ruin ourselves in this way, there has to be a rule, regardless of whether we're in a public or private healthcare system. This is something we don't like thinking about.

Finally, whenever people try to create a system of transitive preferences outside of the mother-system (the economy), the gravity of the currency economy inevitably connects to it and sucks it in, whether we're talking about Ithaca-dollars, or the charade of "no currency" at Burning Man.


SUPPLEMENT - AN EXAMPLE OF HOW CYCLICAL PREFERENCE MONEY-PUMP WOULD WORK, IF IT EVER ACTUALLY HAPPENED

Starting out we have:

Me: 12 green, 12 orange, 12 brown
Her: 12 green, 12 orange, 12 brown


Round 1. I offer her 6 of my orange for all 12 of her brown. Now we have:

Me: 12 green, 6 orange, 24 brown
Her: 12 green, 18 orange, 0 brown


Round 2. I offer her 6 of my brown for all 12 of her green. Now we have:

Me: 24 green, 6 orange, 18 brown
Her: 0 green, 18 orange, 6 brown


Round 3. I offer her 3 of my orange for all of her brown. Now we have:

Me: 24 green, 3 orange, 24 brown
Her: 0 green, 21 orange, 0 brown


Round 4. I offer her 11 of my green for all 21 of her orange. (Give her a good exchange rate and round up. She's irrational, I'll get it back!) Now we have:

Me: 13 green, 24 orange, 24 brown
Her: 11 green, 0 orange, 0 brown


Round 5. I offer her 6 of my brown for all 11 of her green (rounding up again.) Now we have:

Me: 24 green, 24 orange, 18 brown
Her: 0 green, 0 orange, 6 brown


Round 6. I offer her 3 of my green for all 6 of her brown. Now we have:

Me: 21 green, 24 orange, 24 brown
Her: 3 green, 0 orange, 0 brown


Round 7. I offer her 2 of my brown for all 3 of her green (rounding up.) Now we have:

Me: 24 green, 24 orange, 22 brown
Her: 0 green, 0 orange, 2 brown

...you get the picture.

As I was calculating this out I actually found it quite hard to think about the irrational player's decisions. There is value exchange symmetry in rational trading, which is to say, it doesn't matter if I am getting higher-value units or lower-value units. Whereas I would be tempted to say to the irrational player in round 7 above, "Look, why are we going through all this? Why don't you just give me those last 2 brown because they're worth less than themselves!" (Also more than themselves. But I want them, so I wouldn't say that.)

Originally I couldn't see how to benefit from this, even hypothetically - I thought "I could keep the trade going indefinitely but not accumulate anything". The errors were a) I actually had no preference for one color over another, and b) her preference for the "better" one in any pair was arbitrarily small (e.g., she just barely liked orange better than brown), and you can't subdivide M&M's (so with rounding either you could never arrive at having almost entirely fleeced the other party, or it would take too long. On the other hand, if you benefit from the trade itself and have no preferences, and you CAN usefully subdivide, you could still benefit. But I wasn't charging M&M commissions.

There is a total wealth (by my measurement, in units of "browns") of 168 in the game, with each side (by my measurement) starting with 84 brown-units. At the end of each round, with my trades, the value I hold is 84, 126, 126, 124, 162, 156, 166. You actually can't even talk about the other player's total value because what unit do you use to measure it? If we held differing, but rational, valuations - as people do in the real world - then say my daughter values browns twice as much as orange, orange twice as much as green - we'd quickly both wind up with her holding all the brown and me holding all the green. And that would be fine. In fact there have been cases in history where people became worried about the problems that could arise when preferences were different - Isaac Newton noted that because the English and Chinese relative valuations for gold and silver were different, that in a simple system eventually one would end up with all the silver and the other with all the gold, and trade would grind to a halt. But of course the system isn't that simple, and in any event as long as preferences are rational - not circular - it wouldn't matter.

Self-Signalling as Ego Maintenance

Here's an apparent problem with a simple theory that might resolve it.

A lot of human social interaction functions primarily as signalling, even if we're not doing it intentionally. And yet people often seem to signal to themselves frequently. This tendency seems strongest in people with Cluster B character pathology, in particular narcissists, but also to an extent borderline. Could this be best explained as the behavior of a poorly integrated ego reinforcing itself?

Neuropsychiatric Diseases Cause Disproportionate Suffering

I've been poring over disability adjusted life-year statistics for the U.S. One of the things that made me choose psychiatry was that there are a lot of diseases that cause horrendous suffering, and one of the horrendous things about it is that this is suffering that can last a lifetime; they're not directly fatal illnesses in the same way that cancer or heart disease are. This highlights the conflict in medicine between decreasing suffering, and decreasing death. It's underappreciated by many people (including, in my experience, physicians) that these are not the same thing; that in fact there are many times when avoiding one can lead to the other, and vice versa. (One way to think of the job of a physician is to protect and extend the possibility of positive future experience.)

Disability-adjusted life years is the sum of years lived with disability (YLWD) and years of life lost (YLL) due to the disease. Granted, living with disease A for 10 years is likely to cause different suffering than disease B over the same time, but this gives us an idea. And the statistics are given in time per person across the population. Consequently if a disease causes lots of disability but is rare, it will have a lower number than another which causes less disability but is very common.

Some points that emerge from inspecting the data:

1) If you look at the ratio of YLWD to YLL, you can see which diseases kill quickly without much suffering (i.e. lots of people die from it but not many years lived with disability). On the other hand, if you want to focus on diseases that cause disproportionate suffering, you look for diseases with a high disability years to life lost ratio. In decreasing order, the diseases out of the top 50 that have the highest disability years:life lost ratio are: major depressive disorder, bipolar disorder, back pain, anxiety disorders, schizophrenia, alcohol use disorder, and drug abuse, COPD. One quirk is that suicide is listed separately and depression, bipolar and a few others have no stats for years lost, and suicide is how people die from depression and bipolar. So, if you make the simplifying assumption that suicide and MDD have a 1:1 correlation, i.e. everyone who dies from depression dies from suicide and everyone who commits suicide does so out of depression, the list doesn't change that much (now, bipolar disorder, back pain, anxiety disorder, schizophrenia, MDD, alcohol, drugs, COPD.)

The trend here toward neuropsychiatric disorders is clear.

2) Comparing the genders, it's unsurprising to see that women fare better than men. What's more, women's outcomes have improved more over the period 1990-2010, in conditions relating to behavioral risk-taking and impulse control - e.g., road injuries and drug use.

3) Embarrassingly, years per population lived with disability for schizophrenia, dysthymia nad bipolar are all essentially flat for this 20 year period. That's bad. That is not the case for most other major diseases.

4) The rise in death and disability over this period from addiction remains staggering. For added irony, a huge proportion (possibly the majority?) of this represents prescription drug abuse. This represents a major, major policy failure on the part of drug enforcement agencies - you know, the ones that have marijuana scheduled as more dangerous than synthetic opioids. The agencys' position must be: hey, people are suffering and dying, but it's a-okay as long as it's not from street drugs!

The Endowment Effect as a Rational Strategy

The endowment effect is well-studied: people assign higher worths to their own possessions than to same things owned by someone else. That is to say: you wouldn't pay more than $30 for that couch on Craigslist, but when you list your own - same model, same condition - for some reason, you ask (and somehow, actually expect!) $75.

To many of us there are two central features of cognitives biases that make them so interesting. The first is that they're cognitive biases, not cognitive stupidities. We aren't just all over the map due to limited brainpower, as bounded cognition models would suggest; we consistently make mistakes in the same "direction". This consistency (even if it's consistent incorrectness) leads to the other interesting aspect of cognitive biases, which is the extent to which they might actually be instrumentally rational shortcuts in disguise, either being seen out of context or profitable only over the long run. That is, perhaps when we were hunter-gatherers, they were useful. For example, hyperactive pattern detection (type I error) is a terrible thing in the modern age when we're looking for incoming nuclear warheads, but during the Pleistocene, we were stupid and it couldn't get us into too much trouble. Sure, maybe you might end up thinking the gods struck the mountain with lightning because your children cursed a lot that morning, and a thousand other strange things, but we couldn't really do too much about our strange beliefs anyway - but if that one time you saw a shape in the grass that looked like a hyena, and it really was a hyena - well, you still came out ahead.

There's a lot in behavior and medicine like this that only makes sense in evolutionary context, for instance fever. Fever is not something that pathogens do to us, it's something that our bodies actively choose to do to them. In the modern age it's really hard for us to understand how fever can be beneficial, until we remember that merely two centuries ago when, without medicine, we could (and often did) die of fevers. But this is a kind of base-rate fallacy. Fever is a way our body shakes off pathogens, and before modern medicine, that cut in your foot might have a 70% chance of going septic and killing you. If the fever only has a 65% chance of killing you, you still come out ahead of any competitor who didn't have a fever response.

So how could a completely judgment-clouding bias like endowment effect ever be helpful? Finding a group of people who don't appear to have it might point us in the right direction. And indeed, Apicella et al found that Hadza hunter-gatherers in contact with markets show the endowment effect just like the rest of us, but Hadza way out in the bush away from markets do not.

This is pretty amazing - there's a difference in a known bias, even within the same group of people. So we've already learned one thing: the endowment effect is a learned behavior. So either we post-agricultural types are stupid, or we're getting something out of this bias. What's the benefit? And what exactly is different about the two groups of people that makes one group adopt this strategy?

A simple model of markets assumes information symmetry between participants. But in reality, specialization of labor means that the person approaching you to buy your possessions will almost always have better information than the aproachee who's selling them, because the buyer buys (cars, computers, art, etc.) all the time - and if they're initiating the transaction, they are even MORE likely to have better information. Therefore, the endowment effect may be a learned behavior whereby we value our own possessions more highly than is justified on the open market as a defense against information asymmetry.

Here's a concrete example. Imagine you're selling a car. You seek out an offer, and you find another individual buyer. Are you more comfortable that you're getting a fair deal from them than the car dealer? Of course you are. Now imagine you're approached out of the blue by someone who buys cars for a living. Sure, you'd consider it, but only at a very high price where you're sure you're not getting swindled. (This isn't to suggest that the endowment effect occurs consciously, but you can see how when we calculate consciously, we might behave in exactly the way the endowment effect would influence us.)

Consequently, you can imagine the endowment effect as the cushion you need to come out even, when someone with better information than you buys your possessions, especially one who's initiating the deal. And returning to the Hadza hunter-gatherers, we may have identified the relevant difference. Hunter-gatherers are less specialized. If you're a hunter-gatherer, you know just about everybody you could possibly buy or trade something from, and there's not much special knowledge to allow information asymmetry - i.e., everyone is equally smart about the relative value of gazelles and axe heads - so there's no cause to develop such a bias.

This theory makes several testable claims.

1) The more information asymmetry that exists between possession-owner/seller and the buyer, the more the endowment effect gap should be. You think your car is worth more when the car salesman runs up to you on the street initiating and offer to buy it, than when you're selling to someone online with apparently equal knowledge about cars.

2) The endowment effect gap should be larger in markets where there is poorer information, there is less trust, and for goods that are more difficult to value. Complex goods are more difficult to value.

Not central to the theory, but relevant to the fact that this appears to be a learned behavior: children at some arbitrarily young age should not show the endowment effect, because if this differs between humans, it's learned behavior; kids haven't been swindled out of their possessions enough times. (And what is this arbitrarily young age?) Non-hunter-gatherers who nonetheless live in small groups of people with little interchange with other populations should lack this bias. Hunter-gatherers should develop this bias after they come into contact with markets.

There is also a kind of Coasian consideration separate from the theory. Yes, you might have just gotten a good deal for your used Toyota, but now you have a Nissan and there's a utility cost to you of learning how to operate a new car. If that's ALL the endowment effect is, then each individual's ability to learn new behaviors should completely predict the entire strength of the endowment effect in each individual, at least with complex things like cars.

Finite Willpower and The Dual-Self: Behavioral and Imaging Evidence

More evidence that ability to choose delayed gratification (i.e., willpower) is a limited resource. The interesting thing here is the relative activity of the dlPFC. Choosing delayed gratification is associated with activation of a network including the dlPFC, and inactivation is associated with more present-orientation. Demand-avoidance (avoiding tasks which tax willpower) is also associated with low willpower.

Of course the obvious eventual application of this research is to make people behave more rationally by increasing their willpower and therefore the future orientation of the actions they choose. The next step is to understand the mechanism of willpower depletion. Interestingly, in exercise science, there is speculation that what accounts for the latent period between high-impact weight lifting sets is neurotransmitter depletion in the synapse, and restoration on the order of minutes by vesicular transporters. There is also some evidence that neurotransmitter re-uptake inhibitors (specifically SSRIs) can increase the amount of exercise that can be performed until exhaustion (specifically, distance-to-exhaustion in distance runners in my own correspondence). The same thing might be happening in the dlPFC network required for willpower. An initial investigation might be to pharmacologically manipulate neurotransmitter concentration in the synapse in animals models and look at the effect on delay of gratification.

Citation: Kool W, McGuire JT, Wang GJ, Botvinick MM (2013) Neural and Behavioral Evidence for an Intrinsic Cost of Self-Control. PLoS ONE 8(8): e72626. doi:10.1371/journal.pone.0072626

Rhesus Macaques Show St. Petersburg Lottery-Like Behavior

From a PNAS paper by Yamada et al. That is, the macaques were willing to take greater risks for a reward when their pre-existing "wealth" is greater, and the possible lost utility is therefore relatively smaller. The wealth in this case was water - either in the form of a drink of water, or their internal store of water as measured by blood osmolality (the macaque's water bank account). More applications of the St. Petersburg lottery here.

Yamada H, Tymula A, Louie K, Glimcher P. Thirst-dependent risk preferences in monkeys identify a primitive form of wealth. PNAS. Published online before print September 9, 2013, doi: 10.1073/pnas.1308718110.

Personal Risk, Self-Esteem and the St. Petersburg Lottery

There used to be an unsolved problem in economics:  if there were a lottery that consisted of a coin toss, and the pot doubled every day starting from a penny, how much should you pay for a ticket?  (St. Petersburg Russia in fact had such a lottery at once time, hence the name.)  It's not so straightforward.  If there's a lottery where you have a 1% chance of winning a thousand dollars, you should be willing to pay about 10.  But what about this one? 

Standard economic theory used to say that we should be willing to pay a huge, if not infinite amount to buy a ticket, but few people are.  The solution has to do with the fact that the richer you are, the more you're willing to pay for a ticket.  That is to say, once you take into account how much it "hurts" someone to part with a certain sum, then you have your solution.  And it  hurts Bill Gates less to part with $100 than it does you or me; the same sum lost translates to fewer "points off" his utility.  Consequently, we shouldn't be surprised that it's the people who have a lot to begin with who are more willing to venture it to get more.  The perverse effect of this is that the more you have, the more you risk, and the more still you end up making in the end if your bets are rational.

What does this have to do with self-esteem?  Humans are status-driven creatures, which is to say our status is also strongly connected to our utility.  So are there marginal status effects?  Is there a status-equivalent to the St. Petersburg lottery?  Imagine someone who is extremely self-confident, for whatever reason (more on these reasons later).  He has a large reserve of status, at least in his own view of himself.  As with Bill Gates, he will get fewer points off his utility for the same status-losing failure or transgression than the rest of us might.  Therefore, these very self-confident people are more willing to risk status, in order ultimately to gain status.  There are several reasons for confidence that make sense of certain behaviors:


- A confident individual might be "justified" in their view of their status in the sense of a social or professional track record that is publicly recognized, and be willing to go out on otherwise socially unacceptable or status-threatening ventures to achieve more.  The wealthy and successful engaging in ventures that can fail in public are an example of this.

- The individual might be isolated from a peer-group's judgment; he might be a foreigner, or around people in a different socioeconomic class.  A failure seen by you, a mere native, is less skin off their back than if seen by someone from back home or from their good schools.  This might account for the strange burst of assertiveness, innovation and even comfort that people feel when working overseas.

- The individual might just be innately very self-assured.  He's not motivated by status and doesn't much care what others think.  In other words, the status-to-utility conversion factor is small.


These provide testable predictions and if correct, could result in improved innovation.

Strongest Sapir-Whorf Evidence Yet: Economic Implications of Future Tense

Languages with obligatory future tense marking have higher future discount rates, across a host of behaviors. So far the paper seems solid and this observation is pretty amazing. In terms of obvious implications, this sure beats distance and color classification!

The obvious speculation is that future time marking increases the cognitive distance of future plans. It's immediately more interesting that many languages use future tense or future tense-like constructions for their subjunctive. If we put future discounting into procrastination equation terms, we could say that placing future acts into further away, less concrete categories is raising the delay, and/or lowering the expectancy.